FinFET devices

ABSTRACT

FinFET devices and processes to prevent fin or gate collapse (e.g., flopover) in finFET devices are provided. The method includes forming a first set of trenches in a semiconductor material and filling the first set of trenches with insulator material. The method further includes forming a second set of trenches in the semiconductor material, alternating with the first set of trenches that are filled. The second set of trenches form semiconductor structures which have a dimension of fin structures. The method further includes filling the second set of trenches with insulator material. The method further includes recessing the insulator material within the first set of trenches and the second set of trenches to form the fin structures.

FIELD OF THE INVENTION

The invention relates to semiconductor structures and, moreparticularly, to finFET devices and processes to prevent fin or gatecollapse (e.g., flopover) in finFET devices.

BACKGROUND

Semiconductor device manufacturing generally includes various steps ofdevice patterning process. With continuous scale-down and shrinkage ofreal estate available for a single semiconductor device, engineers aredaily facing the challenge of how to meet the market demand for everincreasing device density. One technique was the creation of finFETs,which are formed through a technique called sidewall image transfer(SIT), also known as sidewall spacer image transfer. However, due to thescaling of these devices, there remains a risk of pattern collapse fortight pitch and high aspect ratio configurations, such as the fin orgate modules.

SUMMARY

In an aspect of the invention, a method comprises forming a first set oftrenches in a semiconductor material and filling the first set oftrenches with insulator material. The method further comprises forming asecond set of trenches in the semiconductor material, alternating withthe first set of trenches that are filled. The second set of trenchesform semiconductor structures which have a dimension of fin structures.The method further comprises filling the second set of trenches withinsulator material. The method further comprises recessing the insulatormaterial within the first set of trenches and the second set of trenchesto form the fin structures.

In an aspect of the invention a method comprises: forming trenches insemiconductor material; filling the trenches with insulator material;and forming additional trenches in the semiconductor material to formfin structures, anchored by the filled trenches.

In an aspect of the invention, a structure comprises a plurality of finstructures which are supported by insulator material at a bottom portionthereof, such that the fin structures are partially exposed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in the detailed description whichfollows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention.

FIG. 1 shows a semiconductor substrate with mandrels and respectivefabrication processes in accordance with aspects of the invention.

FIG. 2 shows sidewalls formed on the mandrels and respective fabricationprocesses in accordance with aspects of the invention.

FIG. 3 shows sidewalls with spacing therebetween and respectivefabrication processes in accordance with aspects of the invention.

FIG. 4 shows insulator filled trenches and respective fabricationprocesses in accordance with aspects of the invention.

FIG. 5 shows recessed insulator filled trenches and respectivefabrication processes in accordance with aspects of the invention.

FIG. 6 shows inner sidewalls on sidewalls of the insulator material andrespective fabrication processes in accordance with aspects of theinvention.

FIG. 7 shows fin structures anchored by insulator material andrespective fabrication processes in accordance with aspects of theinvention.

FIG. 8 shows additional insulator filled trenches and respectivefabrication processes in accordance with aspects of the invention.

FIG. 9 shows partially revealed fin structures and respectivefabrication processes in accordance with aspects of the invention.

FIG. 10 shows trenches and other features within the semiconductormaterial and respective fabrication processes in accordance with aspectsof the invention.

FIG. 11 shows liner material formed on sidewalls of the trenches andrespective fabrication processes in accordance with aspects of theinvention.

FIG. 12 shows insulator material filled within the trenches andrespective fabrication processes in accordance with aspects of theinvention.

FIG. 13 shows recesses formed from insulator material and respectivefabrication processes in accordance with aspects of the invention.

FIG. 14 shows inner sidewalls formed on the insulator material andrespective fabrication processes in accordance with aspects of theinvention.

FIG. 15 shows dummy gate structures anchored with insulator material inthe semiconductor material and respective fabrication processes inaccordance with aspects of the invention.

FIG. 16 shows additional trenches lined with sidewall material andrespective fabrication processes in accordance with aspects of theinvention.

FIG. 17 shows additional trenches filled with insulator material andrespective fabrication processes in accordance with aspects of theinvention.

DETAILED DESCRIPTION

The invention relates to semiconductor structures and, moreparticularly, to finFET devices and processes to prevent fin or gatecollapse (e.g., flopover) in finFET devices. In more specificembodiments, the processes described herein ensure that fins of thefinFET and gates are always anchored on one side during fin formationthus preventing fin and/or gate collapse (e.g., flopover). After finreveal, a channel is fully exposed, but at an acceptable aspect ratio.Accordingly, in embodiments, the processes described herein ensures theaspect ratio is limited or the high aspect ratio features, e.g., fins ofa finFET, are physically anchored on one side. Also, advantageously, theprocesses described herein reduce the risk of pattern collapse for tightpitch and high aspect ratio configurations, such as the fin or gatemodule. The processes described herein can also be used to fabricateasymmetrical finFET devices.

The structures of the present invention can be manufactured in a numberof ways using a number of different tools. In general, though, themethodologies and tools are used to form structures with dimensions inthe micrometer and nanometer scale. The methodologies, i.e.,technologies, employed to manufacture the structures have been adoptedfrom integrated circuit (IC) technology. For example, the structures ofthe present invention are built on wafers and are realized in films ofmaterial patterned by photolithographic processes on the top of a wafer.In particular, the fabrication of the structures of the presentinvention uses three basic building blocks: (i) deposition of thin filmsof material on a substrate, (ii) applying a patterned mask on top of thefilms by photolithographic imaging, and (iii) etching the filmsselectively to the mask.

FIG. 1 shows a structure and respective processes in accordance withaspects of the present invention. In particular, the structure 10 ofFIG. 1 shows an oxide or other insulator material 14 formed on asubstrate 12. In embodiments, the substrate 14 can be a siliconsubstrate or other semiconductor material, e.g., any suitable materialincluding, but not limited to, Si, SiGe, SiGeC, SiC, GE alloys, GaAs,InAs, InP, and other III/V or II/VI compound semiconductors.

A plurality of mandrels 16 are formed on the insulator material 14 usingconventional lithography and etching processes. For example, the mandrelmaterial, e.g., silicon, can be deposited on the insulator material 14using conventional deposition methods, e.g., chemical vapor deposition(CVD) process. In embodiments, the mandrel material can be a silicon,e.g., amorphous or polycrystalline silicon. A resist is formed over themandrel material, which is exposed to energy (e.g., light) in order toform openings (patterns). The exposed mandrel material is then etchedthrough the openings of the resist to form the illustrative patternshown in FIG. 1. In embodiments, a width of the mandrel 16 should beroughly a final fin spacing at two times a final fin pitch. For example,assuming a target of a fin pitch of about 25 nm, with a 7 nm fin width,the mandrel should then be at roughly 18 nm (25 nm−7 nm=18 nm) at apitch of 50 nm (25 nm×2 nm=50 nm); although other dimensions are alsocontemplated by the present invention depending on the technology node.

In FIG. 2, a sidewall spacer 18 is formed on the mandrels 16. Inembodiments, the sidewall spacer 18 can be a nitride spacer formed usingconventional deposition and etching processes. For example, the spacermaterial can be blanket deposited on the mandrels 16 and exposedunderlying insulator material 14. An anisotropic etching process canthen be performed to form the sidewall spacer 18.

As shown in FIG. 3, the mandrels (e.g., mandrels 16 shown in FIG. 2) areremoved, leaving behind the sidewall spacer 18. The mandrels can beremoved by using a selective etching process of the silicon material.The spacing 20 between the sidewall spacers 18 is equivalent to thewidth of the mandrels.

In FIG. 4, trenches 22 are formed in the substrate 12 and the insulatormaterial 14, aligned with the spacing 20. In embodiments, the trenches22 are formed by conventional etching processes, e.g., reactive ionetching (RIE). The etching results in silicon features 24, which areroughly two times a fin width plus one fin spacing. For example,following the above example, the silicon features 24 should be 32 nm (2nm×7 nm+18 nm=32 nm), with a pitch of 50 nm; although other dimensionsare contemplated by the present invention, depending on the technologynode.

The trenches 22 are filled with insulator material 26 such as oxide. Inembodiments, the insulator material 26 can be deposited using a CVDprocess or a plasma enhanced CVD (PECVD), followed by an etch backprocess or planarization process, e.g., chemical mechanical polish(CMP). In alternative embodiments, the trenches 22 can be filled using aflowable oxide followed by an anneal process. In yet still additionalembodiments, the oxide fill can be a flowable oxide process, and ifneeded followed by a partial recess process, e.g., etch back, andreplaced with a high quality high-density-plasma (HDP), CVD oxide. TheHDP oxide 26 can then undergo an etch back or planarization process asalready described herein.

As shown in FIG. 5, any remaining oxide or insulator material on thespacers 18 can be removed using a deglazing process. For example, a DHFprocess can be used to remove oxide from a surface of the nitridespacers 18. During the deglazing process, the insulator material 26 canbe slightly etched back to form recesses 28 between the spacers 18. Inembodiments, the etch depth of the recesses 28 can be on the order of 10Å to about 50 Å; although other dimensions are also contemplated by thepresent invention.

In FIG. 6, remaining portions of the spacers can be removed using a hotphosphorus process. This process will expose a portion 26 a of theinsulator material 26 above the insulator material 14 and the substrate12. Inner spacers 30 can be formed on the exposed portion 26 a of theinsulator material 26. In embodiments, the inner spacers 30 can beformed by a conformal deposition process such as an atomic layerdeposition (ALD) process. After the deposition process, the conformalmaterial can be etched by an anisotropic etching process to form theinner spacers 30. In embodiments, the width of the inner spaces can beabout 5 nm to 50 nm, which define the dimensions of subsequently formedfins. It should be understood by those of skill in the art, though, thatother dimensions are also contemplated by the present inventiondepending on the technology node. In embodiments, the inner spacers 30can be a nitride material.

As shown representatively in FIG. 7, trenches 32 are formed in thesubstrate 12 which result in the formation of fin structures 12′. Duringthe formation of the fin structures 12′, the fin structures 12′ remainanchored or supported by the insulator material 26 on opposing sidesthereof. The trenches 32 can be formed using conventional etchingprocesses, e.g., RIE.

In FIG. 8, the trenches 32 are filled with an insulator material 34,followed by an etch back or planarization process (e.g., CMP). Inembodiments, the insulator material 34 can be deposited using a CVDprocess or a plasma enhanced CVD (PECVD), followed by an etch backprocess or planarization process, e.g., chemical mechanical polish(CMP). In alternative embodiments, the trenches 32 can be filled using aflowable oxide followed by an anneal process, and if needed followed bya partial recess process, e.g., etch back, and replaced with a highquality high-density-plasma (HDP), CVD oxide.

As shown in FIG. 9, the insulator material 34 and 26 are recessed topartially reveal the fin structures 12′. In more specific embodiments,any remaining oxide or insulator material on the inner spacers (e.g.,inner spacers 30 shown in FIG. 7) can be removed using a deglazingprocess. For example, a HDF process can be used to remove oxide from asurface of the nitride spacers. Following the deglazing process, thespacers can be removed (e.g., by hot phosphorous), following by theinsulator material 26, 34 being etched back to form recesses 36 betweenthe fin structures 12′. In embodiments, the insulator material 26, 34are recessed using conventional selective etching process as should beunderstood by those of skill in the art. In embodiments, the insulatormaterial 26, 34 are recessed to partially expose or reveal the finstructures 12′. In other words, the fin structures 12′ are not exposedat a full aspect ratio, and remain supported at a bottom portion thereofby the insulator material 26, 34.

FIGS. 10-17 show alternative structures and fabrication processes inaccordance with aspects of the invention. In particular, FIG. 10 shows astructure 10′ which includes trenches 22′ formed in the manner asdescribed with respect to FIG. 4. For example, a plurality of mandrelsare formed on the insulator material 14 using conventional lithographyand etching processes. A spacer 18 is formed on the mandrels. Inembodiments, the spacer 18 can be formed by deposition of a nitridematerial, e.g., using conventional deposition, followed by ananisotropic etching process. The mandrels (e.g., mandrels 16) areremoved, leaving behind the spacers 18 with a spacing 20 therebetween.The trenches 22′ are then formed in the substrate 12 and the insulatormaterial 14, aligned with the openings 20. In embodiments, the trenches22′ are formed by conventional etching processes, e.g., reactive ionetching (RIE), resulting in silicon features 24 which are roughly twotimes a (dummy) gate width plus one (dummy) gate spacing.

In FIG. 11, the trenches 22 are lined with sidewall material 40. Inembodiments, the liner 40 can be a low-k dielectric spacer, e.g., SiCBNor SiOCN. The thickness of the liner 40 can be about 3 nm to 6 nm,depending on the technology node. In embodiments, the liner 40 can beformed by a conformal deposition process, e.g., ALD or CVD, followed byan anisotropic etching process.

As shown in FIG. 12, an epitaxial growth 42 is formed on one side of thedevice. In embodiments, the epitaxial growth 42 can be an in-situ dopedmaterial, e.g., BSiGe for a PFET device and SiP for NFET. In alternateembodiments, the in-situ doped material can be Si:CP or Si:P for anNFET. Following the epitaxial growth 42, a liner can be formed on thesidewall material 40 followed by an oxide fill both of which arerepresented at reference numeral 44. The liner can be a thin nitrideliner (e.g., on the order of 2 nm). The oxide fill can be a flowableoxide process, followed by a partial recess process, e.g., etch back,and replaced with a high quality high-density-plasma (HDP), CVD oxide.The HDP oxide can then undergo an etch back or planarization process asalready described herein.

In FIG. 13, the HDP oxide 44 can be etched back to form a recess 46followed by a deglaze process of the nitride spacers 18. As alreadydescribed herein, any remaining oxide or insulator material on thespacers 18 can be removed using a deglazing process. For example, a DHFprocess can be used to remove oxide from a surface of the nitridespacers 18. In embodiments, the etch depth of the insulator material(oxide) can be on the order of 10 Å to about 50 Å; although otherdimensions are also contemplated by the present invention.

As shown in FIG. 14, the spacers can be removed following the deglazingprocess. For example, any remaining portions of the spacers can beremoved using a hot phosphorus process. This process will leave aportion 44 a of the insulator material 44 and liner material 40 a abovethe insulator material 14 and the substrate 12. Inner spacers 30 can beformed on the liner material 40 a. In embodiments, the inner spacers 30can be formed by a conformal deposition process such as an atomic layerdeposition (ALD) process, followed by an anisotropic etching process. Inembodiments, the width of the inner spaces 30 can be about 5 nm to 50nm, which define the dimensions of subsequently formed (dummy) gate. Itshould be understood by those of skill in the art, though, that otherdimensions are also contemplated by the present invention depending onthe technology node.

In FIG. 15, trenches 32 are formed in the substrate 12 which result inthe formation of (dummy) gate structures 12′. During the formation ofthe (dummy) gate (dummy) gate structures 12′, the fin structures 12′remain anchored by the insulator material 44 and liner 40 on opposingsides thereof.

In FIG. 16, the trenches 32 are then lined with a liner 46. Inembodiments, the liner 46 can be the same or different material than theliner 40. By way of example, the liner 46 can be a low-k dielectricspacer, e.g., SiCBN or SiOCN, formed using conventional depositionprocesses, followed by an anisotropic etching. The thickness of theliner 46 can be about 3 nm to 6 nm, depending on the technology node. Inembodiments, the thickness of the liner 46 can be different than that ofthe liner 40. For example, the liner 46 can be thinner on the sourceside of the device, than on the drain side of the device. Also, inembodiments, the liner 46 can be a low-k dielectric material on thedrain side of the device, and the liner 40 can be a regular or high-kdielectric on the source side of the device. In any scenario, though,the liner 46 can be formed by a conformal deposition process, e.g., ALDor CVD, followed by an anisotropic etching process.

Still referring to FIG. 16, an epitaxial growth 48 is formed on anotherside of the device (e.g., opposite side of the gate structure fromepitaxial growth 42). The epitaxial growth 48 can be different than theepitaxial growth 42 in terms of dopants and dopant concentration, forexample. For example, depending on the epitaxial growth 42, theepitaxial growth 48 can be, e.g., an in-situ doped material, e.g., BSiGefor a PFET device and SiP for NFET. In alternate embodiments, thein-situ doped material can be Si:CP or Si:P for an NFET. In this way, anasymmetrical finFET device can be formed. In embodiments, if one sidehas N-type doping, the other side should also be N-type. But dopantconcentration can be different between the two sides, or one could evenchange the dopant type (bit still keep it N-type if the other side hasN, or P if the other side is P).

In FIG. 17, following the epitaxial growth 48, an insulator material 50can be formed in the trenches 32. In embodiments, the insulator material50 can be deposited using a CVD process or a plasma enhanced CVD(PECVD), followed by an etch back process or planarization process,e.g., chemical mechanical polish (CMP). In alternative embodiments, thetrenches can be filled using a flowable oxide followed by an annealprocess. In yet still additional embodiments, the oxide fill can be aflowable oxide process, followed by a partial recess process, e.g., etchback, and replaced with a high quality high-density-plasma (HDP), CVDoxide. The HDP oxide 50 can then undergo an etch back or planarizationprocess as already described herein.

The structure(s) and processes as described above are used in integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed:
 1. A method, comprising: forming trenches insemiconductor material; filling the trenches with insulator material;forming additional trenches in the semiconductor material to form gatestructures; and providing a doped epitaxial growth at a bottom of thetrenches.
 2. The method of claim 1, wherein the additional trenches areformed alternating with the trenches.
 3. The method of claim 2, whereinthe additional trenches formed in the semiconductor material to formgate structures are anchored by the filled trenches.
 4. The method ofclaim 2, wherein the additional trenches formed in the semiconductormaterial to form gate structures are anchored by the insulator materialin the filled trenches.
 5. The method of claim 1, further comprisingfilling the additional trenches with insulator material.
 6. The methodof claim 5, further comprising recessing the insulator material withinthe trenches and the additional trenches to form fin structures.
 7. Themethod of claim 6, wherein the trenches are lined with a liner material,prior to the filling with the insulator material.
 8. The method of claim7, wherein the additional trenches are lined with a liner material,prior to the filling with the insulator material.
 9. The method of claim8, further comprising providing a doped epitaxial growth at a bottom ofthe additional trenches.
 10. The method of claim 9, wherein the dopedepitaxial growth at the bottom of the additional trenches is provided onanother side of a device with respect to the doped epitaxial growth atthe bottom of the trenches.
 11. The method of claim 9, wherein the dopedepitaxial growth at the bottom of the additional trenches is differentthan the doped epitaxial growth at the bottom of the trenches.
 12. Themethod of claim 1, wherein: forming the trenches comprises: forming aplurality of mandrels on an insulator layer; forming sidewall spacers onthe plurality of mandrels; removing the plurality of mandrels, leaving aspace between the sidewall spacers; and etching into the semiconductormaterial within the space between the sidewall spacers; and forming theadditional trenches comprises: removing the sidewall spacers; forminginner sidewall spacers on upper portions of the insulator material thatfilled the first set of trenches; and etching into the semiconductormaterial within spaces between adjacent ones of the inner sidewallspacers.